Matter and Quantum Systems

The main scientific objective is to advance in the theoretical understanding of complex states of matter where quantum effects are crucial. These include the physics of transition metal compounds and high temperature superconductors, magnetic systems, ultra cold atomic gases and low dimensional semiconductors. Properties studied include the phase diagram, mechanisms of superconductivity, spectroscopic properties, transport properties, effects of disorder. An important objective is to understanding the delicate balance which determines the phase diagram and the new physics that emerges close to phase boundaries. Indeed complex behavior often involves competition between different orders producing interesting behavior close to phase boundaries like gigantic responses to external fields, self generated inhomogeneities or unconventional superconductivity. Competition arise because interactions and the kinetic energy contribute similarly to the energy, therefore these systems are nor in the weak nor in the strong coupling regime which makes them difficult to treat with conventional perturbative approaches. Thus our activities include the development of non perturbative approaches to treat strongly correlated systems.